1. Field of the Invention
The present invention relates to an air conditioning system for use in semiconductor manufacturing factories and the like. More particularly, the present invention relates to an air washer that eliminates dust or harmful gases in air, reduces the supply of pure water used as clean water, and performs humidification with high efficiency of saturation.
2. Description of the Background Art
FIG. 21 shows the outline of a conventional air washer. In FIG. 21, an air washer 1 has a water spray chamber 2 in which air passes through from upstream to downstream. The water spray chamber 2 has a nearly centrally located partition plate 3 that extends in the direction of an air stream (indicated by arrow in the figure). Nozzles 4a of a water sprayer 4 are located opposite the partition plate 3.
In the air washer 1, the nozzles 4a of the water sprayer 4 spray spraying water of pure water so that it collides with the partition plate 3. Dust in the air passing through the water spray chamber 2 collides with the spraying water to reach the partition plate 3 together with the spraying water. Therefore, the dust is trapped by a film of water formed in the surface of the partition plate 3 and then runs down along the partition plate 3 when the film of water falls down.
The above air washer 1 is directed to eliminate the dust in the air and thus has poor efficiency in humidifying the air flowing through the water spray chamber 2.
Specifically, in the cases where air is humidified to be in the vicinity of the saturated state by using the air washer 1, the ratio of spraying water to the flow of air passing through the water spray chamber 2 is required to be set greater than that normally required in eliminating dust. Therefore, a pump for pumping clean water to the nozzles 4a of the water sprayer 4 is required to have extremely large output in order to realize high-saturation humidification.
Now, assume the case where the harmful gas component in the air passing through the water spray chamber 2 is absorbed and eliminated by spraying water. To improve and maintain the efficiency of harmful gas elimination, it is necessary to increase the degree of contact between spraying water and passing air and to hold the cleanliness of the spraying water at a predetermined value and above. In addition, when spraying water is circulated, it is necessary to freshly supply clean water to a circulating system and to hold the concentration of harmful gas component taken in the spraying water at a predetermined value or below.
In the system that circulates spraying water, however, clean water is supplied to a water tank that temporarily stores circulating water, the clean water newly added will function to dilute the concentration of the harmful gases present in the circulating water in the water tank, thus failing to spray the supplied clean water in its fresh state. In other wards, clean water to be supplied as supplementary water is polluted by the harmful gas component in the water tank, thus failing to make full use of the cleanliness of clean water to be supplied.
Moreover, in the cases where all supplementary water is of pure water, a large amount of pure water and a large-capacity apparatus for preparing pure water are needed to increase the initial cost and running cost.